1. Field of the Invention
The present invention relates to a patient interface system, and, in particular, to a patient interface system including a forehead gas supply assembly.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device including a mask component on the face of a patient. The mask component may be, without limitation, a nasal mask that covers the patient's nose, a nasal cushion that rests beneath the patient's nose (such as a “pillows” style nasal cushion having nasal prongs that are received within the patient's nares or a “cradle” style nasal cushion that rests beneath and covers the patient's nares), a nasal/oral mask that covers the nose and mouth, or a full face mask that covers the patient's face. The patient interface device interfaces the ventilator or pressure support device with the airway of the patient through tubing, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. It is known to maintain such devices on the face of a wearer by a headgear having one or more straps adapted to fit over/around the patient's head.
For such patient interface devices, a key engineering challenge is to balance patient comfort against mask stability. This is particularly true in the case of treatment of OSA, where such patient interface devices are typically worn for an extended period of time. Many patients complain about the torque that the conduit or tubing used to supply the flow of breathing gas applies to their mask while they are sleeping. As a patient changes sleeping positions through the course of the night, such torque can cause issues such as discomfort and/or air leaks due to the mask becoming dislodged. Some patients, therefore, try to reroute the tubing above their head for better mask stability. However, the tubing is bulky and no mechanism or method is provided to secure the tubing to the top of the head.
Known patient interface devices that attempt to route the tubing above the patient's head include numerous components that must be assembled, and which increase overall cost. The numerous components also cause the mask to be large and bulky, which is undesirable for appearance, stability on the patient's head, and overall comfort.